In electric arc welding, a “gun” is a flexible, elongated element having a rear end connected to a wire feeder and power source and a front end for a welding torch. The gun includes an elongated flexible conduit directing current and shielding gas from the wire feeder to the welding torch. A welding gun is employed for hand held welding and for robotic controlled welding. Many torches are designed to be water cooled; therefore, the flexible tubing from the wire feeder at the rear end to the torch includes a coolant inlet and a coolant outlet to direct liquid coolant, such as water, into the torch around the torch and then back to a reservoir. The torch must, whether water cooled or not, include a contact tip through which the welding wire from the wire feeder is directed to the welding operation. This tip is highly conductive, generally copper, and supported in a conductive cylindrical main assembly. This assembly establishes physical integrity of the torch and receives power from the power source, through the wire feeder. When water cooling is used, conduits within the main assembly direct water around the assembly to maintain a reduced temperature during the welding operation. Shielding gas is directed from a diffuser forming an integral part of the main assembly into an annular chamber defined by an outer replaceable nozzle. Shielding gas from the nozzle flows around the contact tip so the shielding gas forms a protective barrier between the molten metal of the welding operation and the ambient atmosphere. All of these requirements of a welding torch require complex machined components which substantially increases the cost of the torch and adversely affects the operability of the torch during the welding operation. Furthermore, the welding operation itself creates spatter, especially during short circuit conditions, so the forward end of the torch is subject to substantial deterioration over time caused by spatter together with the tremendous arc temperature involved in the welding operation. All of these adverse conditions create restraints in the design of a torch. They are taken into consideration and substantially improved by the present invention, which involves several novel features for the torch portion of the welding gun. A major objective is improving the torch sot it remains cool, especially for a water cooled torch. The design of the cooling jacket on the torch in existing torches has often proved unsatisfactory. It is recognized that the water jacket or chambers of the water cooled torch should be as close as possible to the arc, since the excessive heat comes from the arc itself. The more the torch is allowed to become elevated in temperature, the more troublesome the cooling problem for the torch. Thus, the water cooling passageways in the torch itself must be designed for efficient cooling of the torch and without affecting the cost and/or the physical strength of the torch. This feature is improved by the novel torch of the invention.
Another problem to be solved by the present invention arises from the overheating of the torch end causing rapid deterioration of the electrical insulation in the torch. This insulation material rapidly deteriorates if overheated. Consequently, in the water cooled torch the cooling jacket or passages should be as close as possible to the arc to prevent excessive heating being transmitted to the insulation of the torch. In both water cooled and air cooled torches, shielding gas is directed into the welding operation from diffuser orifices circumferentially spaced around the torch. This gas has a cooling function as it moves around the main assembly to the contact tip at the welding operation. Consequently, torches require diffuser orifices for shielding gas; however, these orifices must be oriented to prevent unwanted cavitation and turbulence. It has been found that these diffuser orifices should be as close as possible to the welding operation. Such closeness drastically increases the tendency for spatter to affect the laminar flow of shielding gas from the diffuser orifices. The present invention is directed to a torch for solving all of these problems to provide an improved torch for an arc welding gun.